1. Field of the Invention
The present invention relates generally to a method and apparatus for controlling a gain of transmit antennas in a communication system.
2. Description of the Related Art
Communication systems are evolving to provide services for enabling a high-speed, high-capacity data transmission/reception to Mobile Stations (MSs). To enable the high-speed, high-capacity data transmission/reception, various schemes for increasing a data rate and improving reliability of data transmission/reception have been proposed, and one of the typical proposed schemes is an antenna diversity scheme. The antenna diversity scheme, a multi-antenna scheme, is classified into a receive antenna diversity scheme including multiple receive antennas, a transmit antenna diversity scheme including multiple transmit antennas, and a Multiple Input Multiple Output (MIMO) scheme including multiple receive antennas and multiple transmit antennas.
However, when the transmit antenna diversity scheme and the MIMO scheme are used, i.e. when multiple transmit antennas are used, their diversity gain varies according to the way in which a transmission beam vector is generated. That is, the way of generating the transmission beam vector is an important factor affecting performance of the transmit antenna diversity scheme and MIMO scheme. The ‘transmission beam vector’ as used herein refers to a set of transmit antenna gains for each of the multiple transmit antennas, and when the number of the transmit antennas is M, the transmission beam vector includes M elements.
Therefore, there is a need for a scheme of generating a transmission beam vector to maximize a diversity gain in using multiple transmit antennas, i.e. for a scheme of controlling a transmit antenna gain.